Fuse plug, screw type, with indicator



July 19,1927.

- J. B. GLOWACKI FUSE PLUG, SCREW TYPE, WITH INDICATOR Original FiledMayl5, 1922 :Patented July 19,1927.

"UNITED ATES PATENT. eF-me, 1

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FUSE PLUGQSCBEW TYPE, WITH INDICATOR.

Applicatioh sued m 15, 19212, semi No. 560,916. Renewed December 8,i928.

This invention relates to that type of renewable fuses which are adaptedto screw into a socket similar to a lamp socket and are known as fuseplugs.

yet which shall not be likely It is an object of this invention toprovide such a fuse plug with an indicator which shall clearly andreadily show which of a j collection of fuse plugs'has been blown.

It is a further object of this invention to provide a detachablemounting for a fuse strip of a type that may be easily and quicklyinserted in a fuse plug and in which the fuse strip may be very readilyrenewed without" the need of any special tools. 7 It is a further objectof this invention to provide a fuse lug of a type which shall afford anabundant outlet for the products of the explosion when the fuse is blownand i to set fire to the surroundings. I V I Y It is a further object ofthis invention to provide a tortuous and narrow passage which shallrelieve the explosion but shall not permit the flame to emerge.

It is a further object of this invention to provide thetop of the fuseplug with an indicator which shall by its color or condition show whenthe fuse has been blown.

It is a further object of this invention to make a fuse plug of the typedescribed which shall be simple and compact in structure and neat inappearance.

Other and further important objects of the invention will be apparentfrom the dis-' closures in the drawings and specification. The invention(in a preferred form) is illustrated on the drawings and hereinaftermore fully described. On the drawings: Figure 1 is aside elevation plug.

Figure 2 is a central vertical section through the plug.

of the fuse Figure 3 is a bottom plan. view upon an enlargedscale of thefuse carrier.

Figure 4 is aside elevation of the fuse car I rier. v

Figure .5 is an edge view of the closure plate for the fuse carrier.

Figure 6 is an edge view of the fuse. Figure 7 is a top plan view of thefuse carrier with the fuse and .closure plate in position. I

Figure 8 is a bottom plan view of the head of the plug with the shelland spacing plate in place.

Figure 9 is a bottom pleted' plug.

1Ftiagure 10 is a section through the spacing p a a Figure 1L is aplanview of the comsection upon an enlarged scale through the lower endofthe fuse carrier.

Figure 12 is a section upon the line 12- -12 of Fig. 4..

Figure 13 is a-section upon an enlarged scale of the upper part of theplug in a plane at right angles to the section of 2, the indicator beinremoved. i

As shown onthe rawings: The plug comprises a fuse carrier 1 and a head2, bothm'adeofyinsulating material. The fuse carrier isscrewed into theinterior of ascrew-threaded shell"? and the head 2 is screwed onto theexterior "of the same shell, the head being screwed onto; the. shellgure at one end and the carrier screwed into the shell at the other end.K

Thecarrier 1 is made of insulating mate r1al in the shape of a hollowcylinder havin euq a lower end wall 4 which is provided with a circularrecess 5 preferably having a beveled edge. The central part of therecess 5 con-. tains a circular depression 6- in which is formed arectangular depression 7, the core ners of which extend beyond thecircumfer-- GDCO'OIET the depression 6; At'the center of the rectangle 7the depression is crossed by a slot 8 which pierces the wall 4 of thecontainer 1. The interior of the container is a straight cylindricalhollow except that near its upper end it' is provided with a shoulder 9to afford a seat for a metallic closure plate 10. At two diametricallyopposite points the cylindrical wall is cut away down to the level ofthe shoulder as.

is screw-threaded as shown at 16 to fit the screw thread of the shell 3;and the lower part of the carrier isknurled as shown at 17 to facilitatethe screwing of the carrier into the shell.

The strip 18 of fusible metal is provided with narrowed places 19 tolocalize the heating. One end of the strip 18 is folded at a right angleas shown at 20 and. then folded through 180 degrees so that it projectsin the opposite direction as shown at 21. The part beyond the last foldextends beyond the unfolded portion of the strip and is exanded into acircular-member as shown in igure 9 at 22. lVhen inserting the fuse intothe fuse carrier the straight portion 18 is passed through the slot 8 sothat the portion 20 comes to lie in one half of the rectangle 7, and the)ortion 22 fills the circular depression 6. he closure plate 10 is theninserted in place and the slot 23 therein receives the other end of thestrip 18. This end is then bent flat against the outer face of theclosure plate 10, asshown at 24 in Figure 13. The fuse carrier anditsfuse are then ready to be screwed into the shell 3.

Before the shell receives the fuse carrier its spacing plate 25 isinserted in the shell. As shown most clearly in Figure 13, the shellconsists of'a screw-threaded side wall, generally cylindrical incharacter, and an end 26. This end provided with a central opening 27opposite the middle of the spacing plate 25, but not in contacttherewith be-.

cause theplate 25 has an upstanding flange 28 which provides a distancebetween the surface of the plate and the surface of the end 26 of theshell. The other side of the plate has a raised middle portion as shownat 29 which contacts with the turned over end 24 of the fuse strip 18.The spacing plate 25 is provided with holes 30 which connect the spaceinto which the hole 27 opens with the space 15 made by reducing thediameter of the fuse carrier 1. This space 15 is connected with theinterior of the fuse carrier by orifices 32 shown most clearly in Figure12.

The head 2 is traversed by a passage leading to the hole 27 and thispassage is screwt-hreaded for the reception of an insulating tube 33which is shown in section in Figure 2. The lower end of the tube isthreaded to fit the threads in the passage 27. The screw-threadedportion is separated from the rest of the tube by a flange 34 which fitsinto a recess 35 in the top of the head 2. The upper end of the tube isclosed by an end wall. In the illustration chosen this end wall is shownas dome-shaped, but this is not necessary. A little way below the endthe tube has lateral openings 36 and just below the openings 36 is ashoulder so that the upper end of the tube is of slightly smallerdiameter than the part just above the flange.

A cover 37, )referably of gelatine or other light and transparentmaterial, is fitted over the tube 33. The lower end of this cover fitsthe tube 33 and abuts against the flange 34. The part of the cover abovethe shoulder is spaced away from the smaller part of the tube and soaffords a space into which the openings 36 lead. At the upper end of thecover a small perforation is provided as shown at 38. A communicationexists between the interior of the fuse carrier 1 and the outsideatmosphere. This communication is through the holes 32 into the space15, through the holes 30 into the upper part of the plate 25 through thehole 27 into the tube 33, and through the holes 36 into the interior ofthe cover 37; and finally throu h the hole 38 to the outside atmosphere.he cover 37 may of course be omitted and the same venting actionattained.

In assembling the device, the plate 25 is first placed inside, of theshell 3 with the flange 28 against the end of the shell. A pin prick orother depression is then made in the side wall of the shell 3, as shownat 40, to retain the plate 25 in position. The closed end of the shell 3and a portion of the threaded sides of the shell adjacent thereto arethen coated with cement and screwed into the head 2. The fuse 18 is theninserted into the container 1 through the slot 8, as already explained.The closure plate 10 is assed over the other end of the fuse 18 wit theears 12 entering the recesses 13 and the protruding end of the fuse 18is bent over against the plate 10 as shown-in Figure 7. The fuse carrier1 with the fuse therein is then screwed into the shell 3 and the end 18of the fuse contactsv with the raised part 29 of the plate 25. The tube33 is then screwed or otherwise permanently secured into the opening inthe end of a base of the head 2 so that the flange 34 comes into therecess 35. The cover 37 is then placed over the tube 33' and the loweredge of the cover contacts with the flange 34. Preferably the cover iswet just before being laced on the tube so that it will adhere to t etube around the lower edge of the cover.

The fuse plug is then read for. use. It is screwed into a suitable socet. similar to a lamp socket. The screw threaded part of the socketcontacts with the shell 3 and makes one terminal of the circuit. Thecentral cont-act of the socket contacts with the end 22 and forms theother connection to the fuse strip 18. For this reason, the depression 5i made no deeper than the height of the central projecting contact in asocket so that contact is always secured between the end 22 and thispart of the socket. When the current is turned on it flows through theshell 3 to the plate 25, throu h the elevated' part 29; to the end 24the fuse, through the fuse to'the end 22, and so to the other terminalin the socket.

When the current becomes excessive the fuse melts and if the excess issudden and large the fuse may even vaporize suddenly enough to producean explosion. The products ofthe explosion pass out of the interior ofthe container 1 through the holes 32 into the space 15. Emerging fromthe com paratively small holes 32 into the roomier space 15 checks thevelocity of these products. They then pass through the holes 30 whichemerge into the space above the plate 25. Here again the emerging'from ahole into a larger space, accompanied by. change of direction, checksthe velocity of these products. The products then pass u the tube 33,sufier another change of direction to emerge through the hole 36, andfinally come out into the interior of the cap 37. If there wasbutli'ttle force to the explosion the velocity of the products of theexplosion will have largely disappeared by the time this travel isaccomplished and they will emerge through the hole 38 in the form of aslow line of smoke. If however the velocity is greater there may beforce enough to break or displace the; cap 37. Even when the cap is notbroken or-displaced the fumes from the I explosion will discolor it sothat the presence of the fumes is readily recognized.

Even with explosions of considerable vio-' lence the many changes ofdirection and the frequent emerging from hol'es into roomier spacescheck the outflow so effectively that no actual flame reaches theoutside of the plug.

When the failure of light in the house or other occurrence makes theuser of the device aware that a fuse has blown and he goes to the fusebox toeinspect the same, the thin thread of smoke emerging through thehole 38 in the case of the fusg that has blown enables him to quicklyldcate said fuse; or if the observer arrives at the fuse box too late tosee this he can observe which cap 37 is discolored ,or broken, ordisplaced, and

thus readily identify the fuse that. was blown. He then unscrews thefuse from the plug, unscrews'the fuse container from the cap 2, removesthe remaining portions of the strip 18 and inserts a new strip in theway described, then screws the container back into the shell 3 and theplug back into the socket. The whole of this operation takes but a fewseconds as compared. with the many minutes usually used to replace afuse wire.

struction may be varied through a wide range without departing from theprinciples of this invention, and I therefore do not purpose limitingthe patent granted otherwise than necessitated by the prior art.

I claim as m invention:

1. A screw-h secured in one end thereof, said plate having holestherethrough, a fuse container screwed in said shell, a fuse in saidcontainer,said container having holes communicating with the interior ofsaid shell on one side of said plate, and a head screwed on,said shell,said ead having a passage therethrou h communicating with the other sideof said late.

2. In 'a fuse plug, a hollow cylin er, a closure plate at one end ofsaid cylinder, said plate having a slot therethrough, a wallintegralwith said cylinder situated at the opposite end of said closure plate,said wall aving a central slot therethrough and a depression on theexterior immediately surrounding said slot, a fuse in said plugextending through said cylinder with one end projecting through saidslot in said closure plate and the other end projectingthrough saidslotin said wall, and a head on said fuse occupying said depression.

3. In -a 'fuse plug, a hollow cylinder, 9.

fusible element mounted in said cylinder, a'

shell on the outside of said cylinder, a head removably secured jon oneend of said shell, a tortuous outlet from the interior of said cylinderto the outside 'of said head, and a transparent apertured cap positionedover .said outlet.

4. In a fuse lug, a hollow linden a screw-threaded s ell on the outsi eof said cyhnder to engage within a socket, a head screwed on one end ofsaid shell, a dishedreaded shell, a dished plate.

plate secured in one end of said shell and having a plurality of holestherethrough, a closure late removably securedto one end of said cylnder, said plate having a slot there through, a wall integral with saidcylinder oppositely positione to said closure plate, said wall having aslot therethrough and a depression immediately surrounding the exteriorof said last mentioned slot, a fuse extending through said lastmentioned slot, the interior of said cylinderyand the slot in saidclosure plate, saidfuse being bent over after extending through saidlast mentioned slot and frictionally held between said closure.

plate and said dished plate, a head on said fuse occupying saiddepression, said cylinder having ap urality of holes therethrough, saidhead having ahole therethrough, a transparent apertured cap centrallypositioned over said head comprising an insulating tube closed at oneend, said tube being threaded .to fit said hole and having lateralopenings,

J s a transparent cover for said tube. I am aware that numerous detailsof con- J OHN B. GLOWACKI.

